[E]ach service can get a little pushy when it comes to what makes for a perfect push-up. Drop a soldier, sailor, airman and Marine for 20 and you’ll likely see four very different versions. True, the essentials are the same: Legs, back and head straight; arms bending to at least a 90-degree angle; body moving up and down as a single unit. But that’s about where the similarities end.

A Marine, for example, will always start his push-ups by lying flat on his stomach, pushing up into the starting position with a hearty shout of “Marine Corps.” Soldiers, sailors and airmen, however, will drop straight into the “front-leaning rest” position, with the body up and arms fully extended. Ever predisposed to making things more challenging, the Marines must also double dip, doing two push-ups for every one rep counted.

The Army and Air Force say feet can be up to 12 inches apart. Sailors, on the other hand, must keep them together. Soldiers must wear shoes; sailors can take them off. Soldiers can put their hands where they’re comfortable. Marines must put them directly under the shoulders. Airmen must put them out slightly wider. Sailors can place their hands anywhere between the two...

Meanwhile, the Army’s new regs for its PT test say soldiers can do push-ups on their fists (the other services can’t), but soldiers are not allowed to wear glasses (the others don’t say).

For the push-up to count, Marines must briefly touch their chests to the floor. Soldiers and airmen can if they want, but never to rest or bounce to build momentum. Again, the Navy is the strictest — a sailor’s PRT is over if his chest touches the deck.